Distributor



May 11, 1943. R. v ATwooD x-:rAL

DISTRIBUTOR Filed May 13, 1942 4 Sheels-SheelI l ,l W .WIT .www QN m m mw E we b NN w ruf@ l um: m mm n Sn l e am A 0N mm1 M r HA J um. m \N\ \l||| q f HN HU I I l l I l I l l Il l /M Q 1 .#lww NN |f f Il n -if N l I w Nw lill SN. all u Nm. ,N0 \%m NN. N w l ha Sw .u wmdw NN J www MM. v

U @w Ev MuiW|L DISTRIBUTOR Filed May 13, 1942 4 Sheets-Sheet 2 May 11, 1943. R. v A-rwooD Erm.

DISTRIBUTOR Filed May 13, 1942 4 Sheets-Sheet 3 MA R7' INVENTORS Fog/EPT K Ammo JpA/Fy/f.

ATTOR EYS 4 Sheets-Sheet 4 May 11, 1943- ln. v. ATwooD ErAl.

DISTRIBUTOR Filed May 13, 1942 Patented May 11, 1943 UNITED STATES PATENT OFFICE DISTRIBUTOR Application May 13, 1942, Serial No. 442,842

8 Claims.

This invention relates to improvements in ignition apparatus for internal combustion engines and, more particularly, to the distributor mechanism thereof.

The invention is especially adapted for use in connection with the ignition apparatus of'airplane engines and is herein disclosed by way of illustrative example, in connection with a 16 cylinder, V-type airplane engine, firing at irregular angular intervals of rotation of its crankshaft. A

The invention has for an object the provision of a distributor having a stationary feed ring connected to the high tension terminal of the ignition apparatus and provided with a plurality of contacts angularly spaced in a circular series and a cap having a plurality of contacts angularly spaced in a circular series and adapted for connection one to each of the spark plug wires, together with a rotor having means thereon for connecting terminals of the rst series one at a time to terminals of the second series.

The invention also has for an object the provision of a distributor of Ithe class described wherein individual electrodes, one at each end of the rotor, are provided, and are adapted to function alternately in the work of connecting contacts of the iirst series to contacts of the second series.

The invention has for another object the provision of a distributor of the class described wherein the connections to the various spark plug wires are made at irregular angular intervals of rotation proportioned to the irregular angular intervals of rotation of the engine crankshaft at which the engine fires.

The invention has for another object the pro'- vision of a distributor arranged withina casing which may be sealed up, when required,` and which has means for connection to a supercharger when required.

The invention has for another object the provision on the rotor of fan blades located adjacent the electrodes for the purpose of circulating the air in the distributor and particularly of removing ionized air from the zone in which the contacts and electrodes are located.

Another object of the invention is to provide in connection with the fan blades described, cooperating stationary vanes on one of the contactbearing rings, such vanes enhancing the action of the fan blades on the rotor and also serving, by their location between successive contacts as barriers.

A further object ol the invention is to provide a distributor in which all of the spark plug wires are led out through a radio-shielding tube located at its point of connection to the distributor coaxially of the latter.

A further object of the invention is to provide in a distributor of the general class described a weatherproofed ventilation and drain passage connected to the distributor chamber.

A further object of the invention is to provide a combined drain and ventilation passage for the distributor chamber and a valve for controlling such passage, characterized in that the valve automatically closes whenever the distributor i's being supercharged.

These and other objects will best be understood as the detailed description proceeds and they will be pointed out in the appended claims.

The invention will be disclosed with reference to the accompanying drawings, in which:

Fig. 1 is a sectional elevational view of an ignition apparatus embodying the invention-this view being taken on the line I-I of Fig. 2;

Fig. 2 is a top plan view with the cover and the rotor of the distributor removed;

Fig. 3 is a sectional plan view taken on the line 3-3 of Fig. 1;

Fig. 4 is a fragmentary sectional elevational view taken on the line 4-4 of Fig. 2;

Fig. 5 is a fragmentary sectional elevational view taken on the line 5-5 of Fig. 3;

Fig. 6 is a fragmentary cross sectional view of the distributor cap;

Fig. '7 is an end elevational view of the distributor rotor;

Fig. 8 is a fragmentary sectional elevational view taken on the line 8-8 of Fig. 3;

Figs. 9 and 10 are fragmentary sectional views both taken on the line 9 9 of Fig. 2; f

Figs. 11 and 12 are cross sectional views taken on the lines I I-II and |2-I2 respectively of Fig. 10;

Fig. 13 is a fragmentary cross sectional view taken on the line |3--I3 of Fig. 3;

Fig. 14 is a bottom plan view of a ment in the distributor cap; and

Fig. 15 is a fragmentary sectional elevational packing eleview of a ventilation and drain valve for the distributor.

Referring to Fig. 1, these drawings, the distributor and the associated breaker point mechanism, are contained Within a metallic casing C which entirely encloses them and completely shields them so far as radio interference is concerned. This casing has a peripheral wall 20, an end Wall 2l suitably fixed as by screws 22, to one end of wall 2D and a cover 23 suitably fixed as by screws 24 (Fig. 3) to the other end of wall 20. This casing provides within it a distributor chamber D, the same being formed between the cover 23 and a cross wall 25 inside the casing, which wall forms one end wall of chamber D. This wall has openings 25 therethrough. The rotor shaft is shown at'26 and it is mounted in suitable bearings in Awalls 2l and 25. The cover 23 has a tubular portion 23 providing a central opening coaxial with shaft 26. This opening is closed by the elbow 21, which forms part of a conduit for the spark plug wires w. The elbow is suitably fixed to cover 23, as by screws 28.

The space in casing C between the -walls -`2| and 25 may, if desired, and as shown, house thfeispark generating means. As illustrated, such means includes primary and secondary coils 25 and 3E! respectively, which in this case form part of a magneto and are energized intermittently at proper Iintervals thereby. The coils arehoused in aplastic case f3f| 'and secured, .as by screws 32., to partiti'on 25. The wire 33, shown -in.Fig. 2, as lconnected to partition 25 and thereby grounded, -is .connected to one terminal :of Aboth coils. The wire 54 fin Fig. y2 forms the other terminal :of `the `,prismaryfcoil. Theother `terminal of the secondary coil includes .1a Wire (Fig. 1) .and -a metal but- -ton 35 co'nnected thereto. These :are located in the flowerportion kof la Asubstantially -L-sh-aped .ini

sulating tube 31 which at itslower end is cast in the plastic case v3i-l fand .the upper end =oi which .rises vertically into the lower part of chamber D. The other magneto elements (notshown) may -be contained within .casing-C, below'thecoil-case '3 I The dist-ribntor i comprises two contact-.bearing rings of insulating .material andan intervening :brush-carrying rotor. The innerring 38 is an annulus and has `a plurality of legs Y39, one of whichfs -shown in Fig. 9, which engage 'wall 25 andare secured thereto, las by screws Ernbedded `in ring 38 is lametallic feed ring 4| '-(Fig. .2) 'from whichextend a ;pluralit;y(8 inthis case) of contacts 42 which Yare arranged fat equallyspaced angular inter-vals (45 in this case) in a circular series. One of these contacts 42 is :shown rin detail in Fig. '5. Fig. 2.shows that 'these contacts extend in a direction 'parallel to the Vaxis vof the Vring v3.8 and .are `encompassed by amarginal circular i'ange v43 on such Ting. vpoint (Figs. 1 vand 2*) ,zthe'feeidring 4| :is enlarged to receive a stud 44 (Fig. l) tbearing a :spring i4'5 which .makes `connection with the liigh tension terminal of coil 38. As shown, this connection `nra'd'e through fthe rinterm'e'diaryroi a resistor nform of ya'sha'llow cup yor cap .having a vbase A48 and a circular marginal flange 49 which .telescopes and closely fits the ange v4.3 of the Ainner .ring V38. 'The Itwo ringshave complementary fin- 'ished :shoulders which .abut lwith 'a close `lit as fshown.

The 4closely intertting .rings prevent .dashing from vthe contacts to 'themetallic 'casing 25. This :outerming ris connected vto-fcover 23 fby At one f in a turbine.

insert 5| in the base 48. This base has an axially-directed and outwardly extending hub portion 52 which passes through the central opening in the cover. This hub portion is provided with a plurality of sockets 53 for the spark plug wires w. In this case, there are sixteen such sockets and they are arranged in two coaxial circular series. The base 48 of the outer distributor ring carries a circular series of contacts 54 (16 as shown in Fig. 3). These contacts (Figs, 8 and 1'3) project inwardly from the base 48 of the -outer ring in a direction parallel to the axis of such ring. As shown, these contacts are integral with wires 55 which are embedded in the base 48 and connect the contacts, one to each of the terminals in the base of the sockets 53. These sockets are arranged in two coaxial circular series of eight so that eight of the wires 55 are of the length .shown in Fig. 8 to reach the sockets of the inner series and eight of them are of the .length shown vin Fig. 13 to .reach the sockets of `the-outer series. .In Fig. 3,-each contact ,has beside it a numeralindicating the number ofthe cylinder to which it is to be connected. The yrelativelocations of the two series Iof contacts are .shown in Fig. `S-each contact 42 rlying centrally between the `two adjacent contacts .54. Located betweeneach pairiof contacts 54 except :thetwo lowermost ones shown in.Fig. 3is van integral .and radially extending barrier56 (see also Fig. 6). These barriers also cooperate like the fixed bladesof va'turbine with movable blades carried :by the distributor rotor.

'This rotor (Figs. 3 and A8) comprises fa diametrically extending member'51of insulating material, -xedcentrally bycap screws 58 to a flanged hub 59, which is'splined to the shaft'26. AEnut 60 (Fig. l) clamps flange59 against .the inner race 6l of the ball bearing 62 andthe race :6| against a ange 63 on the shaft. The rotor has :brushes (Fig. "8) one .on each end thereof to :cooperate with both the contacts 42 v`and 54. 'On-e brush (see Aalso Fig. 7:) `hasca terminal 64 fto cooperate with vthe contacts 54 of Atheputer-'series and a terminal 65 to :cooperate Withthe .contacts of the vinner series. These terminals'are electrically interconnected by an integral .bent portion 66 which is embedded in the plastic material of which arm 51 is made. The other brush -hassimilar terminals 64 and85 anda similar :connector 66 interconnecting them in a similarmanner.

'These 'terminals 64 and V65 and the terminals164' and 65 are 'located 'at 'angularlyispaced intervals -'being'separated .by an angle-equal r'to that .between any contact .42 and either ofthe two ad'- jacent contacts 54, as will be rclear 'from Fig .3. These terminals T64 and 55 aswell asthe terminals 64 and 65 `are also 'located in Idiierent transverse planes. The outer faces ofeach brush 'terminal which moves 'inrclose relation to the contacts is finished as are also the contacts. 'The trailing `face of each such 'terminal is exposed (Figs. 13 and 7) as this takes any burning which may occur from the spark when Vthe latter is `drawn out as the brush and contact separate. There is a lateral Ibarrier 61'between the inner and outer terminals of each brush.

' The rotor arm carries near both its outer-ends 4and projecting from both faces thereof fan blades 68 which are mounted generally radially of the `rotor and spaced by a small :angle behind the trailing face of each brush terminal. The outer blades move in close proximity to the 'barrier blades 55 and cooperate therewith somewhat-as The purpose o'f the "blades is to stir up the air within the distributor chamber D and particularly to drive out from the peripheral region thereof the air which has been ionized by high tension discharges of electricity therethrough and to replace such air by air drawn from the inner portion of the chamber. Ionized air increases the liability to leakage because it is more easily penetrated by the sparks than is unionized air.

Referring now to Figs. 8 and 13, each spark plug wire w has xed on and electrically connected to the inner end of its metallic portion a metallic washer 69. Each wire 55 has an axiallydirected screw-threaded end 10 which enters theA base oi' a socket 53. A spring 1| is screwed onto each said end 10 and held in place thereby; When each wire w is thrust into its socket 53, the washer 69 engages and slightly compresses the spring 1|, thereby making and maintaining good electrical contact between each wire w and its wire 55.

'Ihe spark plug wires w pass through holes in a rubber disc 12, having integral tubular extensions 13 one for and inserted into each socket 53. The hole in each extension closely ts the outer and insulated portionof its wire w. 'I'hs member 12 is separately shown in Fig. 14. The washers 69 are large enough in diameter to engage the inner ends of these extensions 13 (Fig. 13) and prevent the wires from being pulled out of the rubber member. This member also has a rim portion 14 which fits into the space between the hub 52 and the sleeve 23. The disc 12 also hafs a. central projection 15 of irregular cross section to fit in a hole 15 of the same cross sectional shape in hub 52, whereby the disc may be so lo` cated so that the proper wires w enter the proper sockets 53. A disc 16, also perforated to receive the wires w, serves as a gland plate, being engaged by a shoulder in elbow 21 and serving, when the elbow is bolted in place, to compress the rubber disc 12. The rubber disc, which is compressed between plate 16 and the outer end face of hub 52 is caused to bulge against each wire w and against the inner wall of elbow 21, thereby sealing off the elbow from the distributor chamber.

Suitable breaker mechanism is provided as best shown in Fig. 2. As shown, there are two breaker arms which are operated in proper timed relation from an eight-lobed cam 11, formed on the inner end of hub 59 a-nd thereby fixed to shaft 26. One breaker arm 18 is pivoted on a stud 19 fixed toa plate 80. This plate is turnably mounted on the hub 8| which supports the upper bearing for shaft 26. Screws 82l passing through slots in plate 80, are threaded into wall and serve to fix the plate in its various positions of adjust'- ment. The other breaker arm 83 is pivoted on a stud 84 fixed to a smaller plate V85. The latter is turnable about hub 8| and angularly adjustable relative to plate 80. Screws 86 passing through slots in plate 85 are threaded into plate 80 and serve to clamp plate 85 to plate 80 and hold the two together in their various positions of relative adjustment. An eccentric 81 located in a notch in plate 85 is pivoted in plate 80 and serves as a means for moving plate 85 on plate 80 when screws 86 are loosened. Arm 18 carries'at one end a breaker point 88 and at the other end a cam iollower 89 of relatively small angular extent. Arm 83 carries at one end a breaker point 90 and at the other end a cam follower 9| of relatively large angular extent. The xed breaker point 92 with which point 88 cooperates is i'lxed to lit has turned 'l1/2 the breaker points .of operation of the breaker points.

a plate 93 turnable about stud 19, when the clamping screws 94 are loosened by turning the eccentric 95, in a manner similar to that described in connection with plate 85.

The point 88 is connected by a spring 95' to an insulated terminal 96 and the spring acts to press the follower 89 against cam 11. The fixed breaker point 91 with which point 90 cooperates is similarly mounted on a plate 98 adjustable by an eccentric 99 about the axis of stud 84 and held to plate in various positions of adjustment by clamping screws |00, in a manner similar to that described in connection with plate 85. A spring |0| connects the point 90 to an insulated terminal |02 on plate 98. Thus, both breakers may be moved together about the axis of shaft 28 or either one may be moved independently of the other about said axis. The degree of breaker point opening is controlled by adjusting the plates 93 or 98 on plates 80 and 85 respectively.

'I'he two breakers are electrically connected in parallel. The described terminal Wire 34 of the primary coil is connected to insulated terminal |02 and thus to movable breaker point 98. A wire |03 connects terminal |02 to the insulated terminal |04 of a condenser within a metallic case |05 to which the other terminal of the condenser is connected and which is fixed by screws |06 to plate 80 and thereby grounded. A wire |01 connects the wire |03 and insulated terminal |04 of the condenser to the insulated terminal 96 and thus to movable breaker point 88.

The breaker arm 18 with the narrow shoe 89 is arranged to be so actuated by cam 11 that its breaker points 88, 92, remain open for 30 and closed for 15 of each 45 cycle of movement of the cam. The breaker arm 83 with the wide shoe 9| is arranged to be so actuated by cam 11 that its breaker points 90, 91 closed for 7 of each 45 cycle of operation. The breaker arms are so spaced that when breaker arm 18 is midway in its angular dwell in closed position the breaker arm 83 is midway in its angular dwell in open position. Assuming that cam 11 is turning clockwise as viewed in Fig. 2, when from the illustrated position, the arm 18 will be points 88 and 92. still be engaged by The wide shoe of arm 83 will a high point of the cam and accordingly, the breaker points and 91 are open. Thus, the opening of breaker points 88 and 92 will cause an opening of the primary circuit and the production of a spark. When cam 11 has moved ll/2 from the illustrated position, 90 and 91 will engage. At the same time, the breaker points 88 and 92 remain open. When cam 11 has moved 221/ from the illustrated position, the breaker arm 83 will have been moved to open its breaker points 90 and 91 at a time when the breaker points 88 and 92 are still open. Thus, the opening of points 90 and 91 will cause an opening of the primary circuit and the production of a spark. This second spark occurs 15 after the first spark. When cam 11 turns still further into a position 371/2 from that illustrated, the breaker points 88 and 92 will close but the breaker points 90 and 91 remain open. When cam 11 turns still further and assumes a position 521/2 from that illustrated, the breaker points 88 and 92 will be opened at a time when the breaker points 90 and 91 are still open, thus again opening the primary circuit and producing another spark at angular interval of 30 after the second spark. This completes one cycle It will thus remain open for 38 andA moved to open the breaker beseen that `the breakersvcause V.the primary .cir- -cuit to be opened falternately `at .different .interiva'ls-rrst at 15 vand then-at .36". The magneto, if one is used, will of course -be' timed "to :produce leffective changes o'f fiux 'at similar intervals, .timed -to correspond with the-opening lof the primary .circuit bythe 'breaker :mechanism as above described.

VA connection has beenprovided for the usual :ground switch, which when closed short circuits 7.the primary coiland prevents the generation of sparks. Referring to Fig. 4, a conducting strip YI-58 -is fixed atone end 4to plate 8|] by one of the .cap screws 8-2, whichserve -to -clamp plate -80 to wall 25, an'd is insulated from plate 85, wall 25 and screw 82 as indicated. A wire |59 (Fig. 2) connects .said end of istrip 408 to `the insulated .terminal 55 above described. The other end of Vstrip |58 -underlies the ring V38 of :insulation Vas clearly shown -in Fig. 4. A wire H0, adapted for connection at one end to the ground switch, has its other end electrically connected to a metallic cap i secured on the inner end of an insulator H2, through which the wireextends. The insulator is removably mounted. in a nipple ||3 secured in casing and vhas a flanged outer end .to seat in Ya counterbore in said end. The insulator A| l2 is held in place by a cap I I4, which compresses packing ||5 against said flanged end to yseat it 4in thecounterbore and also to seal the ,joint between the wire and insulator. When lthe insulator ||2 `is mounted in place as shown, the cap lengages one end of a spring ||6 and slightly Acompresses the-same. This spring at its other end, is screwed 4in a threaded stud I 11 fixed :to the under face of strip |08 Iand depending therefrom.

The distributor ychamber -is provided with an 'opening H8 (Fig. 2) to receive a pipe, such as `I I9, which connects with 4a supercharger, whereby the pressure within the chamber may be maintained -at the desired predetermined value. When the supercharger is used, it -will be understood .that all other outlets from the chamber are closed.

A drain for the distributor chamber is also provided, whereby condensation may be removed by fgravity flow or blown out if desired. The longitudinal center line of the casing -23, defined -by the longitudinal axis of shaft 25, is normally inclined about 15 fdegrees to the horizontal so that theouter end (right hand end as viewed in Figs. 1 and 8) is lower than the inner end. At the lower outer end of -thedistributor chamber,

fa threadedopening |25 .(Figs. l0 and 15) is provided. A hole |2| in ring 43 provides communication between the interior of distributor cham- ;ber D and hole |20. This hole may ,be closed 'with a plug when a supercharger is used-the operator removing the plug and draining the chamber before the start of a flight and then replacing the plug. f Another expedient is shown in Fig. 15. A :fitting |22 is screwed into hole |20. This fitting "has a through passage |23 with a counterbored Aoutlet end and, in the counterbored part is slidably mounted avalve |24, `yieldingly held to its seat by a spring |25. A cap |26, acting as a seat for spring |25, also carries a frusto-conical mem- -ber |21 to cooperate with valve |24 and has outlets |28. Normally, the spring raises the valve out of engagement with member |21, leaving the 'outlet open for drainage of water or for entrance `Aof air for ventilation purposes. However, when the superchargeris used, the pressure of the air :ion valve |24 vmoves/the same'toward and holdslit against the 4member |21, thereby automatically closing the Youtletwhen such closure is necessary.

A weatherproofed ventilation opening is shown in Fig. l0. A tube |29, having an axial `passage |30 and a flange |3| is :screwed into hole |2J'un4 til the flange abuts `the hub on casing V23. A

cap, Ahaving an end wall |32 and a peripheral Wall |33, is mounted on the tube as shown-beingsecured thereto by a cap screw |34. The cap forms with the tube and `its flange, an 'annular chamber |55 which is in constant communicationwith passage |30 by means of a hole |35 extending diametrically through tube |29. The screw |34 closes the outer end of passage |30. Two .series of holes are `formed in the cap, one on each side of passage |36 and :spaced therefrom by a dis tance at least as great as the 'diameter of 'hole |35. The holes of one series are marked 131. They are formed in the peripheral wall 33 ofthe cap. The holes of the other series are marked |38. They are formed inthe 'end wa'll |32 of :the cap as shown in Fig. 12. The axes of the holes |31 and |38 -are located in vradial `planes which are different than the radial plane in which the axis of hole |36 is located. The 'radial distance between the outer periphery of tube |29 andthe inner periphery of wall |33 is at least as great as, and preferably .somewhat greater than, the diameter of holes |31 or |38. The arrangement is such that rain, which Ymay drive in through any of the openings |31 or |38, cannot readily enter the hole |36 and reach the passage |30 which connects with the distributor chamber.

; This is true irrespective of what position thecasing 23 and the cap |32|33 may assume. This cap may be vertically pointed, either up or down, approximately horizontal as shown, or at any angle in between these extremes. The purpose of the arrangement is to allow ventilation of the distributor without allowing entrance of water. It may be used with or without the valve device of Fig. 15.

In operation, the shaft 26 is driven at one vhalf crankshaft speed. Sparks are produced sixteen times during each revolution of shaft 25, `the angular intervals between successive sparks Abeing alternately l5 degrees and 30 degrees, corresponding respectively to 30 and 60 degree intervals of rotation of the engine crankshaft. The breaker mechanism, as above described, serves to open the circuit of the primary coil 29 .at the intervals described. The distributor rotor, moving with the breaker cam 11, successively connects the Yfeed ring to the spark vplug wires in l'the proper order and alternately at intervals fof '15 and 30 degrees. For example, the rotor arm V51 turningclockwise -as vviewed in Fig. v3, will after 71/2" of movement connect the contact 54 for cylinder No. 8 with the feed ring. This is done by the brush G4, 65, 65 at one end ofthe vrotor-the terminal |54 moving opposite said contact 54 and the terminal 65 moving opposite a contact 42 of the feed ring. This position of the rotor corresponds to the above described position of the cam 11 when .the breakers are actuated to open the primary circuit after rI1/2'move ment of the cam from the illustrated position. As the rotor continues to turn in a clockwise direction, the brush 64', 65', 66' at the opposite end of the rotor will connect the contact V54 for No. 7 cylinder to a feed ring Contact 42. This occurs after the rotor has moved l5 degrees from the last-described spark-producing position and at'thesame time that the breakers open the pri.-

mary circuit. Continued movement of the rotor over a 30 degree interval will bring the brush 64, 65, 66 into position to connect the contact I for No. 6 cylinder to the feed ring. This occurs simultaneously with another opening of the primary circuit by the breaker mechanism. The rotor, in continued movement, successively connects the contacts 54 to the feed ring in the following order: 5, 4, 3, 2, 1, 16, 15, 14, 13, 12, 11, and 9-thus completing the cycle. The connection is made rst by one brush and then by the other and alternately at and 30 degree intervals. Y

The distributor is completely shielded to prevent interference with radio. The shielding is accomplished by a metallic casing which cornpletely surrounds and encloses the distributor and the breaker mechanism. This casing, comprising the members 20, 2| and 23 effects the result in an eiective manner because the number of joints in the casing are reduced as low as possible. Joints in the casing increase the resistance and thus reduce the effectiveness of the shielding. The elbow 21 which is part of a conduit forming part of the so-called harness" used on airplane engines, also extends the shielding to the spark plug Wires as is desired. The connection of this elbow to the distributor cap coaxially of the same is important. It allows one to use simply two different lengths of contact wires, such as 55, as against many prior art constructions in which each Wire is of a different length.

The distributor construction is important because of its simplicity of construction which adapts it for quantity production at low unit cost. Two moldings of suitable insulating material are provided, one having embedded therein the feed ring and contacts and the other the spark plug contact-bearing Wires 55, together With an intervening rotor, bearing brushes only at its ends. These elements are readily and inexpensively manufactured and readily and easily assembled into the casing which encompasses them. No electrical connections to the moving rotor are required. All contacts are outside the rotor. The contacts of both series are equidistant from the axis of the rotor and the brushes on the rotor leave the contacts of both series at the same angular velocity, providing a double break in the high tension circuit to each cylinder. The arrangement is especially suitable for engines having a large number of cylinders because the contacts can be arranged in a circular series of large diameter and this enables ample spacing between successive contacts. Also, the arrangement of brushes on the rotor enables the solution of the problem of distribution at uneven angular intervals.

Thus the invention provides an improved distributor especially adapted for use in connection with airplane engines and accomplishing the objects hereinabove set forth.

What we claim is:

1. A distributor, comprising, a casing, a shaft mounted therein, a first circular series of contacts mounted in said casingin coaxial relation with said shaft and located between two parallel planes transverse to the axis of said shaft, a second circular series of contacts also mounted in said casing in coaxial relation with said shaft and located between two other parallel planes transverse to said shaft and spaced axially from the first-named planes, an electrical connection between all the contacts of the first series and located between two adapted for connection to a source of supply of electricity, connections for spark plug wires leading one from each contact of the second series, a rotor arm ixed to said shaft, an electrical connector fixed to and insulated from one end of said arm and adapted intermittently to connect contacts of the first series one at a time to contacts of the second series.

2. A distributor, comprising, a casing, a shaft mounted therein, a iirst circularseries of contacts mounted in said casing in coaxial relation with said shaft and located between two parallel planes transverse to the axis of said shaft, a second circular series or" contacts also mounted in said casing in coaxial relation with said shaft and other parallel planes transverse to said shaft and spaced axially from the first-named planes, an electrical connection between all the contacts of the rst series and adapted for connection to a source of supply of electricity, connections for spark plug wires leading one from each contact of the second series, a rotor arm xed to said shaft, an electrical connector fixed to and insulated from one end of said arm and terminating with contacts which are spaced axially as well as angularly with respect to said shaft and which are adapted intermittently to connect contacts of the first series one at a time to contacts of the second series.

3. A distributor, comprising, a casing, a shaft mounted therein, a first circular series of contacts mounted in said casing in coaxial relation with said shaft and located between two parallel planes transverse to the axis of said shaft, a second circular series of contacts also mounted in said casing in coaxial relation with said shaft and located between two other parallel planes transverse to said shaft and spaced axially from the first-named planes, an electrical connection between all the contacts of the irst series and adapted for connection to a supply source of electricity, connections for spark plug wires leading one from each contact of the second series, a rotor arm xed centrally to said shaft and extending diametrically of said casing and series of contacts and carrying one on each end thereof a connector insulated operating alternately rst series one at a time to contacts of the second series.

series, each connector having its terminal ends angularly spaced by the same amount as the angular spacing between one contact of the first series and the two next adjacent contacts of the second series.

5. A distributor, comprising, a circular series oi contacts, a rotor arm having. at one end a terminal for cooperating one at a time with the contacts of said series, a casing enclosing said contacts and arm, saidcasing having an inlet for connection to a supercharger and a drain outlet and being otherwise closed, a valve for opening and closing said outlet, said valve being biased to open position and being movable to closed position by air pressure during supercharging;

6. A distributor, comprising, av circular series of contacts, a rotor arm having at one end a terminal for cooperation one at a time with the contacts of said series, a casing enclosing said contacts and arm and having a drain outlet', a tube xed to'said casing and having an axial passage communicating with said outlet atf one end and having the opposite end closed, said tube having a plurality of holes therein extending radially from said axial passage to the periphery of the tube, a casing xed to said tube and providing an annular chamber surrounding said tube and closed at both ends, said casing having a plurality of openings through its peripheral Wall spaced rearwardly from said radial holes by an axial distance greater than the diameter of said openings, said casing having a plurality of open? ings through the outer endY wall thereof spaced forwardly from said radial holes by. an axial distance greater than the diameter of said open-.

ings, all said openings having their axeslocated in diierentr radial'planes than'those in which the axes of said radial holes Vare located, the radial distance between the outer periphery of the tube and the `innerperiphery of; said casing being at least as great as the, diameter of;v said openings. M Y

7. A shielded distributor, comprising,axrnetalg4 lic casing having a peripheral wall and anend wall connected at one end thereof tosaid peripheral wall, said casing affording1 withindt a4 dise tributor chamber closed at one end, aring4 of insulating material xed in said ,casingA andbearing a circular seriesof contactss ashaft mounted in said end wall coaxially of said series and carry,. ing a rotor arm, a metallic coverA secured to .the other end of the peripheralwallandclosing the other end of said chamber4 exceptI for a single legliiaeto opening located coaxially of said shaft, a second ring of insulating material; Xed ltos'aid cover and bearing a second seriesv of contacts located coaxialls7 of said shaft, said rotor arm having on its end a contact to connect the contacts ofE the first series one at a time to contacts of the second series, the second ring having a substantially cylindrical part extending through the opening in said cover, terminalsockets provided in said last-named part, onefor each contact ofY the second series and electrically connected one to each thereof, a metallic conduit having an elbow xed to said cover and closingthe openingtherein, and spark plug wiresin said conduit and connected one to each of said sockets.

8. A shielded distributor, comprising, a metallic casing havingV a peripheral wall and an end wall connected atv one; endY thereof to saidz peripheral wall, said casing affording withirrita distributor chamber closed at one end, a ring of insulating material fixed in said casing and bearing a circular series of` contacts,Y a shaftA mounted in said, end Wall coaxially of said series and carrying a rotor arm, a metallic cover se,- cured to the other end of the peripheral wall and closing the other end of said chamber except for a single opening located coaxialiy of saidshaft, a second ringrof insulating material fixed to said cover and bearing a second series of, contacts, located coaxially of said shaft, said rotor arm'. having on its end a contact to connect thelconr.- tacts of the rst series one at a time top-con`` tacts of the second series, the second ring having a substantially cylindrical part extendingthrough, the opening in said cover, terminal sockets mounted in said last-named part one forv each Contact of the secondseries and electrically connected one to each thereof, a metallic-conduit having an elbow fixed to said cover and closing the opening therein, spark plug wires in said conduit and co-nnectedone to each of said sock'- ets, a seal ring of ilexible materialY and a gland plate each perforated to receive-said wires and clamped between said elbow and saidv part of, the second ring, whereby the seal ring ls compressed and bulged against said several wires; and against the inner Wall of the opening in the cover to seal oi communication between said conduit andthe distributor chamber.

ROBERT VV; ATWOOD. SIDNEY' K. SMART.- 

